The invention relates to a device for separating multiple doses from an extruding device for extruding synthetic plastics.
Specifically, but not exclusively, the invention can be applied to supply the synthetic plastics intended for forming the annular liner of a closure for containers, such as, for example, a lid for a jar or a cap for a bottle.
In particular, reference is made to a device for separating a multiplicity of doses of plastics and then for depositing the doses of plastics, for example directly inside a closure for containers, such that at least one part of the deposited doses has an annular arrangement. This annular arrangement will in fact facilitate the formation, for example through compression of the doses, of the internal sealing liner of the closure for containers.
Forming an annular liner by means of a process that comprises separating a multiplicity of doses from an extruder, placing the doses in a circular arrangement and subsequently forming the annular liner by compressing the doses is already known.
The known technique disclosed above nevertheless has some limits and drawbacks.
In the first place there exist certain structural and/or functional constraints that limit the maximum number of the doses and/or the minimum diameter of the liner.
With reference to FIG. 1, with A the various dose separating elements are indicated and with B the corresponding extruder outlets from which the plastics exit. In general, a dose separating element is concave and faces forwards, with reference to the advancing of the separating element to the outlet of the extruder.
A first constraint is the diameter D of the dose, which in general must not be less than the height of the dose.
Another constraint is the thickness of the wall of the separating element, which will be, generally, between 0.75 and 1 millimeter.
A further constraint is the distance between a separating element and the holes of the extruder outlets, which distance must in general be greater than at least 0.7 millimeters.
Taking account of at least these constraints, it is very difficult, if not impossible, to form liners with a very small diameter Dp, especially if such liners are relatively very heavy, i.e. require the use of a large quantity of plastics.
Further, it is not possible to increase over a certain limit the number of doses of plastics (and the consequent number of extruder openings and of dose separating elements) for a certain liner diameter Dp.
Each of documents US 2007/134361, EP 1101587, EP 1101586 and US 2009/127076 discloses a device according to the preamble of claim 1.